Tube-control unit



Jan. 10, 197281, 39655,@99

H. H. FROST Y TUBE CONTROL UNIT Filed Deo. 8, 1924 2 Sheets-Sheet l 0,2 E wwf/a@ if .f

wif/655 @.51

Jan.1o,192s. 1,655,899

H. H. FROST TUBE CONTROL UNIT File'dlneo. s, '1924 2 sheets-sheet 2 Patented Jan. 10, 1928.

' UNITED sTATEs '1,655,899 PATENTI OFFICE.

HERBERT H. FROST, 0F CHICAGO, ILLINOIS, ASSIGNOR, BY LIESNE ASSIGN'IEEJNTS,- T0 CHICAGO TELEPHONE SUPPLY COMPANY, 0F ELKHART, INDIANA, A CORPORATION 0F DELAWARE.

TUBE-CONTROL UNIT.

My invention relates to control devices for radio circuits and the like.

In the operation of a. radio receiving set employing one or more thermionic tubes it 1s a necessary to control a number 'of variables, one of which is the current ilow through, or voltage impressed upon, the filament of the tube. This is generally done by means of a rheostat It is desirable that this control be made smooth and easily regulable mechanically so that minute and accurate electrical control of the heating of the hot cathode or filament may be had.

Another control that is desirable, `is the variation of B-battery potential impressed upon the plate circuit of the tube. For this purpose a potentiometer is employed, such potentiometer being bridged across the A- i battery and a variable contact made on the potentiometer resistance for the plate circuit in order to vary the amount of A-battery potential which is added to the B-battery potential. Such control may be supplemented by taps on the B-battery, so that the B-battery voltage may be varied to as fine a degree as may be desired.

According to my present invention, both such controls are united in a single instru- 5 ment. This provides the convenience of control from one point and effects .a valuable saving of space and work in mounting. It effects also a shortening of connections and a simplification of the circuit electrically as well as mechanically.

Now, in order to acquaint those skilled in the art with the manner of Iconstructing and operating a device embodying my invention, I shall describe in connection with the accompanying drawings one embodiment in which the invention may appear.

In the-drawings Fig. 1 is a side elevational view of a device embodying my invention;

Fig. 2 is a rear elevation of the same;

Fig. 3 is a front elevation of the same;

Fig. 4 is a longitudinal section centrally through the device and control knobs therefor; and

Fig. 5 is a circuit diagram illustrating Athe o eration of my device.

l In ig.-1 I have shownl the control unitl as mounted upon a panel 1. The device comprises a base member 2 of moulded insulation which includes a central disc 3 `of in'- sulation and an outer cylindrical barrel or flangemember 4 with a radial flange 5 extending outwardly beyond the cylindrical barrel member 4 to mount the vernier resistance 6 which consists of a single wire laid in a groove and extending from a point indicated at 7 in Figure 2 to the point 8, also indicated in Fig. 2. At the end 7 the wire is passed through a radial drill hole in the flange or cylindrical member 4 to form one terminal, and at the opposite end the wire is likewise passed through a drill hole at 8 and then extends along* theydiso 3 to the point 9 where it extends through a perforation in the disc 3 and passes through to the opposite side,'as indicated at 10 in Fig. 3, where it is fastened under the head of the screw 11.

lIt will be observed that the rear side of the flange 4 has a pair of slots 12 and 13 in the vedge thereof, and that bolt/s 14 and 15 lie in said slots and they have their heads on the inside of the barrel 4, lying on the internal cylindrical surface 16. Adjacent these screws there areLv provided steps or recesses 18 and 19 to receive the heads of the bolts 20 and 21, these bolts passing through holes drilled in the ange or barrel 4. Between the steps 18 and 19 there is formed a recess 22 to receive the head of the bolt 23. A ieXible strip of insulating material 24, which is wound with the potentiometer resistor 25, is disposed upon the outer cylindrical surface of the barrel member 4, and the ends of the' strip with the conductor thereupon are clamped' under the angular stop and contact members 26, these parts being held by suitable lock nuts 27 and termi- 'nals 28 and 29 being threaded upon the outer` ends of the bolts 12 and 13` to form suitable binding posts. In like manner, suitable knurled thumb nuts 30 and 31 are threaded upon the outer ends of the bolts or screws 20 and 21, suitable lock nuts being provided under them to hold the bolts in place. The bolt 20 forms the binding post for the end of the vernier wiref6, while the bolt 21 and its thumb nut 31 form the binding post for the terminal of the rheostat resistor 32. This rheostat resistor 32 is wound upon a iiexible strip of ber or the like 33, and saidystri with the resistor 32 thereupon, is ldispo in a circular slot 34, which 1s formed at the junction of the disc 3 with the barrel member 4. Between the ends of the strip 33 there y terminal for the-contacting spring 37, this lus sring'having a saddle portion 38 fitting on t e outer cylindrical surface of the barrel member 4 and being held by the lock nut under saidthumb nut 36. This spring is.

arched over the'flange 5 and stop 36, and extends down to the center of the body 2 Where it has a contact point 39 in' substantial axial alignment with the disc 3 and barre 4.

A central metallic'sleeve bearing member 40 is molded in place iu the disc 3 and it serves as a bearing for the hollow shaft 41, which shaft has a reduced portion 42 joining the main part of the shaft. at the shoulder 43. The sleeve 40 has Va head 44 upon the backside of the disc 3 and has, an internal counterbore which is threaded as indicated at 45 for the reception of the threaded thimble 46 which has a head 47 at the outer end thereof. This thimble 46, together with the rear art of the sleeve 40, comprises a bearing or the hollow shaft 41, this shaft extending forward out of the thirnble 46 and being connected to the control knob 48.

.The thimble 46 is ofthe same character as a telephone jack thimble, and it has a hexagen Ahead adapted to be engaged by a vwrench for 'drawing the body 'or base 2 against the panel 1, as indicated inv Figs. 1 and 4.`

The front edge of the barrel member 4 is provided witn a stud 49, which is ada ted to enter a recess in the panel 1 for holdmg the body member 2 against rotation and for locating or centering the same.- It'will be noticed that thethimble 46'draws the panel tight against the base and it closes the slots 12 and 13 in the front edge of said barrel member 4.

The hollow shaft 41 extends rearwardly througha collar member 50 which lits closely upon the reduced portion 42 of the shaft,-

and""`at its outer end" the reduced portion 42 has a neck which receives the hub-51 of the Vernier arm 52, the outer endof which is bent over, vas indicated at 53, andV has the terminal finger 54 hooked over the front-'edge of said flange 5. This bent portion4 53 has la pair of contact fingers 56 radially engaging the fiange 5 and hence makingrontaet with the Vernier conductor 6. The shaft of the Vernier arm 52 has a longitudinaleorrugation to stiien the same. This arm is preferably made of German silver. The reduced neck is riveted over thevedges of the hole in the hub 51- to holdfseeurel the'vernier arm 52 to 'the end of the hol ow shaft 41,

52 to provide a lost motion connection between said Vernier arm 52 and the rheostat arm 59. At its outer end the rheostat arm 59 bears upon the edge ofthe strip' 33 and its resistor 32, so as to make contact with the same. Now it is to be observed that the4 Vernier arm 52 may be moved through substantially 360 degreesless the distance required by the stop 36. The distance between the stop 36 and the point 7 where the rheostat conductor terminates is great enough to permit the sprin fingers 56 of the Vernier arm 52 to run o of said Vernier conductor 6. so as to break contact therewith. At the Sametime, the Vernier arm 52 draws with it the rheostat arm 59 to a point on the strip 33, from which the rheostat resistor 32 has been removed. so as, to disengage the rheostat arm 59 from the4 rheostat resistor 32 to break contact therewith. New, it is to be observed that the resistance of the Vernier resistor 6 is so proportioned to the resistance of theturns ofthe rheostat resistor 32 that the lost motion connection of the arm 52 with the arm 59 )ermite the insertion or phenolic condensation product, and this insert comprises a sleevc'adapted to fit closely on'the hollowwshaft 41 and"haVing1a-set. screw 63 for clamping the knob 48 to said hollow shaft 41. The knob 48 has a central opening therethrough, and through this central opening in the knob 48 and through the hollow shaft 41 extends the central shaft 64, which, at its front end, is fastened to the potentiometer knob 65, said potentiometer knob having a metal insert 66 containing a set screw 67 for securing the knob to said shaft 64. At. its reaixend the shaft 64 extends out of thehollow shaft 41 and in turn has a reduced portion 68 providing a shouluis der/against. which rests a metallic washer 69 and an insulating washer 70. A potenapogeo tiometer arm 71, which has an opening through the hub of the same to receive a washer of insulation 72, is clamped between the insulating washer 70 anda second insulating washer 73 by means of the nut 74, which is threaded upon the reduced portion 68 of the rear end of the central shaft 64. A U-shaped strip of insulation 75 is clamped between the washer 73 and the surface of the potentiometer arm 71. The rear end of the potentiometer arm is bent back over the nut 74 and the end of the shaft 68, and this U-shaped strip of insulation 7 5 serves to insulate said rearwardly bent portion 76 from the nut 74 and the cooperating end of the shaft. This rear end of the potentiometer arm is extended into axial alignment with the shaft 64 and has a slight depression formed to receive Vthe Contact point 39 onl the stationary spring 37 which leads to the binding post 36.

The outer end of the potentiometer arm 7l extends out over the hook end of the vernier arm 52 so as to clear the same, and then is bent back to form a finger 77 which contacts edgewise Withthe turns of the potentiometer resistor 25 and is adapted to engage the stops 26 at either limit of its movement without breaking contact with said potentiometer resistor.

The knob 48 has a pointer 78 secured to the metal insert 62, as by means of a rein which the .unit of my invention may be connected in a suitable receiving circuit.

The rheostat 32 and Vernier resistance 6 are connected in series through the arms 52 and 59 in the A-battery circuit, which includes the A-battery shown in Fig. 6 and the filament F of the tube 80. The binding post 31 is connected by wire 81 to the positive terminal of the A-battery, while the binding post 30 which leads to the rheostat resistor 32 is connected by wire 82 to the positive terminal of the ilamentpF. The negative pole of the battery is connected to the negative terminal of the filament F by wire 83.

The potentiometer resistance 25 is bridged across the terminals of the A-battery by wires 84 and$85 which lead respectively from the terminals 29 and 28 to the positive and negative poles of the battery A. The

potentiometerl contactarm v71 is connected' to the selected point on the potentiometer I have provided a simple and compact con-A trol unit, performing the dual function of a rheostat control for the filament current and a potentiometer for varying the voltage upon the receiving circuit.

I do no intend to be limited to the details shown and described, except as such limitations may appear in the appended claims.

-I claim 1. Ina control unit of the class described,

the combination' of'a cylindrical body of insulatioma central shaft mounted therein, a potentiometer strip having a resistor `Wound thereupon, said strip being disposed upon the outside of said cylindrical body, terminals mounted on the body at each end of the strip and holding the same .upon the body, a contacting arm mounted on the shaft, said arm having a finger engaging the resistor on said strip, said arm having back around the end of the shaft to provide a contact axially in line with the shaft, and a stationary contact spring-mounted on said body between said terminals and having a contact engaging said rst-named Contact.

2. In combination, a substantially cylindrical body of insulation having a pair of terminals mounted thereupon, a potentiometer strip on said-body clamped under said terminals, said strip comprising a resistor, a central shaft guided in said body and having a contacting arm secured "thereto, said arm cooperating with said resistor and having its inner end bent around the shaft end to form a contact substantially axially in line with the shaft, a third terminal on the body between'aforesaid terminals, and a contact spring extending from said third terminal yieldingly into engagement with said axial contact.

3. In combination, a cylindrical body of insulation having a potentiometer strip disposed upon the outside surface-of the same, a potentiometer resistance on said strip, terminals for clamping the strip and connecting with the resistor mounted on said body, a central shaft, a potentiometer arm having a central apertured hub and a rearwardly extending portion, said hub bein clam in insulated relation tol said sha sai rearwardly extending portion being bent over `the end of the shaft into substantially axial aligmnent with' the same, and a stationary contact spring mounted on the body of in an end bent sulation cooperating with said bent portion of said arm..

4. A cylindrical body of insulation having a potentiometer strip disposed u on the -outside thereof, a resistor on sai( strip, terminals for clamping the strip on the body, said terminals being in `contact with the resistor, a radial flange at the rear end of the cylindrical body, a hollow shaft extending through the body, a Vernier resistance on said fiange, an arm secured to said hollow shaft, said arm cooperating with the Vernier resistance, a central shaft extending through said hollow shaft, and a potentiometer arm insulated from both of said shafts and extending out over said flange and into engagement with theresistor of the potentiometer strip.

5. In combination, a cylindrical body of insulation having a radial liange, a potentiometer resistance disposed uponsaid cylindrical body, terminals for said resistance mounted upon said body, said terminals comprising stops, said cylindrical body having a circular recess, arrheostat resistor disposed in said recess, a hollow shaft extending axially of the body, a Vernier resistor disposed viding a shoulder for engagement with said upon said flange, a Vernier arm secured to the inner end of said hollow shaft and cooperating with the Vernier resistor, a rheostat arm' having 'a lost motion connection with said Vernier arm, a terminal on said body connected to one end of the rheostat resistor, another terminal connected to the endof the Vernier resistor, a central shaft extending through said hollow shaft, a potentiometer arm secured to said central shaft and extending over the flange and into engagement with the potentiometer resistance, and a stationary contact spring secured to a terminal on said body, sald contact spring tentiometer arm, sai potentiometer'arm and 'having constanten agement with the po contact spring being insulated 'from both' of said sha 6. In combination, a cylindrical body of insulation having a radial ange, a potentiometer resistance disposed upon said cy- -lindrical body, terminals for said resistance mounted -upon said bod said terminals comprising stops, said cylindrical body havin a circular recess, a rheostat resistor dispose in said recess, a hollow shaft extending axially of the body, a Vernier resistor disposed upon said flan v cured to the inner end of said hollow shaft and cooperating with the Vernier resistor,

we, a Vernier arm seattacca spring having constant engagement with the potentiometer-arm, said potentiometer arm and contact spring being insulated from both of said shafts, and a stop on said body under said stationary contact spring for limiting the motion of said Vernier arm.

7. ln combination, a hollow shaft, a bearinn sleeve for the same having a shoulder,

said shaft having -a reduced portion profirst shoulder for limiting the axial mot-ion of said shaft, a collar mounted on said reduced portion, a spring washer mounted between said collar and said bearing, a rheostat arm connected to said collar, said rheostat arm having stop fingers extending rearwardly from the same, and a Vernier arm secured to the rear end of said hollow shaft and extending between the stop fingers of the rheostat afm.

8. In combination, a hollow shaft, a bearin sleeve forthe samehaving a shoulder, said shaft having a reduced portion providing a shoulder for engagement with said first shoulder for limiting the axial 'motion of said shaft, a collar mounted on said reduced portion, a spring washer mounted between said collar and said bearing,a rheostat arm connected to said collar, said rheostat arm having stop fingers extending rearwardly from the same, a Vernier arm secured to the rear end of said hollow shaft and extending between the stop fingers of the -rheostat arm, a central shaft lying in said hollow shaft, said central shaft having a reduced portion providing a shoulder, a nut on the outer en -of said reducedl portion a potentiometer arm clamped in insulated relation between said nut and said shoulder, said arm having a portion* disposed axially beyond the end of said centrall shaft, and a stationary contact spring for engaging said axially disposed ortion.

In witness whereo I hereunto subscribe my name this 2nd day of December, 1924.

- HERBERT H. FROST. l 

